added argument-based constructors for initial data classes.  moved constants into their own file.  added a new trick (since I'm not iterating the conformal metric) to renormalize the ordinary metric by the iterated conformal value -- this improved the bowen-york solver stability.  changed bowen-york angular acceleration to always be 3D no matter what dimension we're simulating -- so it will use correct rotations in 2D sims.  fixed up the test case program a bit more.  added the option to pick what columns you want to output.  added a script for diff'ing tables of numbers and returning relative and absolute errors.